1. Field of the Invention
The present invention relates to organic light-emitting display devices. More particularly, the present invention relates to packaging of organic light-emitting display devices.
2. Description of the Related Art
Generally, an organic light-emitting display device comprises a substrate comprising a pixel region and a non-pixel region, and a container or a substrate opposed and disposed to the substrate and bonded to the substrate with sealant such as epoxy for encapsulation.
In the pixel region of the substrate a plurality of organic light-emitting devices are formed between a scan line and a data line in the form of a matrix. The organic light-emitting devices comprise an anode electrode and a cathode electrode; and an organic thin film layer comprising a hole transporting layer, an organic light-emitting layer and an electron transporting layer, which are formed between the anode electrode and the cathode electrode.
However, since the organic light-emitting device includes organic material, it may be vulnerable to oxygen and since the cathode electrode is made of metal material, it is easily oxidized by moisture in the air to possibly deteriorate its electrical characteristics and/or light-emitting characteristics. To prevent this, a moisture absorbent material may be mounted on a container manufactured in the form of a can or cup made of metal material or a substrate of glass, plastic, etc., in the form of powder, or coated or adhered thereto in the form of a film, thereby removing moisture that penetrates from the surroundings.
However, the method of mounting the moisture absorbent material in the form of a powder has problems that include such things as manufacturing process complications, material and process cost increases, increased thickness of a display device, and difficulty in applying to a front light-emitting display configuration. Also, the method of coating or adhering the moisture absorbent in the form of a film has problems in that it is limited in its ability to remove moisture and the adhesive force between the sealant and the substrate may become weakened due to possible outgassing during the curing process, lowering the durability and the reliability of the device.
Therefore, in order to solve such problems, there has been proposed a method of encapsulating an organic light-emitting device by forming a sidewall with frit. International Patent Application No. PCT/KR2002/000994 (May 24, 2002) discloses an encapsulation container wherein a side wall is formed with a glass frit and method of manufacturing the same. U.S. Pat. No. 6,998,776 discloses a glass package encapsulated by adhering a first and a second glass plates with a frit and method of manufacturing the same. Korean Patent Laid-Open Publication No. 2001-0084380 (Sep. 6, 2001) discloses a frit frame encapsulation method using laser. Korean Patent Laid-Open Publication No. 2002-0051153 (Jun. 28, 2002) discloses a packaging method of encapsulating and adhering an upper substrate and a lower substrate with a frit layer using laser.
When using a method of encapsulating a light-emitting device with a frit, after bonding a sealing substrate to which a frit is applied to the substrate on which the light-emitting device is formed, the frit is melted and adhered to the substrate by irradiating laser thereon. However, if the laser is not irradiated at a constant power and speed, the frit may be bonded to the substrate in a state where the frit is not completely melted so that the interface adhesive force between the frit and the substrate may be partially weakened. If the frit is delaminated in the defective portion, it may cause an infiltration of oxygen or moisture.
Also, when a substrate with a large diameter is used for manufacturing a large screen, the width and height of the frit may need to be increased. In this case, in order to melt and adhere the frit to the substrate, a laser with a high power may need to be irradiated thereto. However, if the laser power is increased, the frit may be cracked by the high heat, or since high heat is transferred to the light-emitting device in a portion adjacent to the frit, the function of the light-emitting device may be lost or degraded.
The discussion of this section is to provide a general background of organic light-emitting devices and does not constitute an admission of prior art.